Don't laugh Don. It isn't polite.
But, and this butt is of proverbial Barr proportions, I just do it.
First and foremost is it's almost impossible to have perfect duplication of bends because of the composition of the metal involved. So accepting that and the fact that the mind of the viewer will compensate for small imperfections, again, just do it.
Aluminum tube of about hundred and twenty thousandths will be the most forgiving and easiest to form. I would lay out a radius on the work bench. This might be anything from taking the end of a cable reel and using it to making a metal ring off of the pattern of a automobile wheel. Just something with a large radius. You want this firmly attached to the work bench. Then at a point that allows you the most room you put in a pin to work the tubing against.
It would look something like this ). The dot being your pin.
Now what I use is my hip. Sounds silly but you have a lot more control with your hip versus your arms when it comes to making repeated consistant moves. I'd wedge the aluminum between the ) and the . I'd then push against the )
The amount you push is miniscule, a lot less than what you'd think you'd need. The more less is more better.
Then I'd move the tubing about three inches and then push again trying to do exactly the same amount, the reason for the hip instead of the arm. Repeat as needed.
What I'd do is plan on when purchasing the material to allow for some incredible edible, learning curve consumable you might say. I'd play with this piece to get a feel for just how hard to push to get the curve I want without making it obviously a series of straight lines tied together.
Then I'd do one. First I'd bend the big curve. Turn the tubing around and pushing against the curve I just made I'd do the smaller tighter radius. I'd do the other. They don't match. That's when you bend this here or that there this one or the other until you have a matched close enough pair.
A couple of things will interest you about this process. First thing it is a little like investing in your retirement. If you look at just one segment it don't look like you've done squat. But when you look at it cumalatively you've done a lot.
The second thing is you will find a rythm for working the bend that will take over and the next thing you know you'll be as surprised as the wife about how easy it was and how nice it looks.
It wasn't until listening to a professional athelete describe being in the zone where it's all reaction and oneness with the event that I understood what was going on when I work. I become part of what's happening. I'm along for the ride I guess would be the best way to describe it. Even though I'm behind the wheel and it's my foot on the accelerator I'm still just a cog on the gear in the big picture.
If you can tig aluminum you have been there. You might not have recognised it but you were there. When you're doing the bend the same thing happens and it is fun.
There's a set of gates in Farmersville Texas that you'd like. They are nine feet tall where they meet in the middle. It's a pair covering a thirty eight foot opening.
The top rail is two by four fourteen gauge rectangular tubing. They've got the kind of curve you want. But instead of filagree I used a custom design between the top and second horizontal rails.
The customer had foolishly told me to just do what I do for design. They just wanted something nice. Easy for them to say. They are a drilling company with the big pier drilling rigs.
As I was looking at the finished frame I still hadn't found the design for the middle. The traditional scrolly stuff just didn't seem appropriate. Then I noticed an auger bit in my yard in profile. That design is so simple. It's like holding your hand with our fingers tight together like a flag on each side of vertical piece. So that's what I did. I cut out a shishkeepotfull of these pieces and welded them to three quarter verticals and you talk about being lucky? I got lucky.
Now to the point of that story. Think about how you would bend two by four fourteen gauge rectangular tubing without using brute force.
I cheated.
I took out the portaband and started making cuts. Everyone else I've ever seen use cuts to make a bend have cut the inside of the radius. Me being me I did the outside. I'd make a series of cuts then pull my bend where the gap would be about twice to three times max the width of the saw blade each cut. Now it doesn't sound like much. But think of giving your kids advice on retirement.
For the long sweeping bend I put the cuts farther apart and then for the tight bend coming back I put them much closer together.
Once I had two pieces almost exactly alike, nothing's perfect, I check all the time. I then tacked across the saw cuts. Then it was serious welding one oh one until it was done two oh two followed by grinding three oh three with polishing four oh four on it's butt saying "faster".
Now I understand some folks read that, draw a picture in their mind, and go off in a wonder land. Wondering why oh why would anyone do so much work.
You have to had been there. There when it was just an impossible dream. There when it was a maybe. There when it might work. There when it should work. There when it's gonna work. There when by gawd it did work. There when the customer was admiring it and then asked how it was done. There when I explained that it was really only a thing and not really that hard at all.
